U.S. patent application number 14/374133 was filed with the patent office on 2015-01-15 for method and system for coverage enhancement of uplink voip.
The applicant listed for this patent is ZTE (USA) Inc.. Invention is credited to Yifei Yuan.
Application Number | 20150016430 14/374133 |
Document ID | / |
Family ID | 48905730 |
Filed Date | 2015-01-15 |
United States Patent
Application |
20150016430 |
Kind Code |
A1 |
Yuan; Yifei |
January 15, 2015 |
METHOD AND SYSTEM FOR COVERAGE ENHANCEMENT OF UPLINK VoIP
Abstract
Apparatus and methods for improving a coverage of an uplink
Voice over IP (VoIP) transmission of a wireless device are
disclosed. A wireless device assigns a first hybrid automatic
repeat request (HARQ) process to a first VoIP packet of the
wireless device. The wireless device then assigns a second HARQ
process to a second VoIP packet of the wireless device. The
wireless device then transmits the first and second VoIP packets to
a base station.
Inventors: |
Yuan; Yifei; (Iselin,
NJ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ZTE (USA) Inc. |
Richardson |
TX |
US |
|
|
Family ID: |
48905730 |
Appl. No.: |
14/374133 |
Filed: |
January 28, 2013 |
PCT Filed: |
January 28, 2013 |
PCT NO: |
PCT/US2013/023368 |
371 Date: |
July 23, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61592290 |
Jan 30, 2012 |
|
|
|
Current U.S.
Class: |
370/336 ;
370/329 |
Current CPC
Class: |
H04L 1/1887 20130101;
H04L 1/1877 20130101; H04L 65/1053 20130101; H04L 1/1812 20130101;
H04L 1/1861 20130101; H04W 24/02 20130101; H04W 72/1263 20130101;
H04L 1/1822 20130101 |
Class at
Publication: |
370/336 ;
370/329 |
International
Class: |
H04L 1/18 20060101
H04L001/18; H04W 24/02 20060101 H04W024/02 |
Claims
1. A method for improving a coverage of an uplink Voice over IP
(VoIP) transmission of a wireless device, the method comprising:
assigning a first hybrid automatic repeat request (HARQ) process to
a first VoIP packet of the wireless device; assigning a second HARQ
process to a second VoIP packet of the wireless device; and
transmitting the first and second VoIP packets from the wireless
device to a base station.
2. The method of claim 1, further comprising bundling the first and
second HARQ processes over four transmit time intervals.
3. The method of claim 2, wherein the first HARQ process and the
second HARQ process are allocated to different physical
resources.
4. The method of claim 2, wherein the first and second HARQ packets
are transmitted using semi-persistent scheduling.
5. An apparatus for improving a coverage of an uplink Voice over IP
(VoIP) transmission, the apparatus comprising: a wireless device
configured to: assign a first hybrid automatic repeat request
(HARQ) process to a first VoIP packet of the wireless device;
assign a second HARQ process to a second VoIP packet of the
wireless device; and transmit the first and second VoIP packets
from the wireless device to a base station.
6. The apparatus of claim 5, wherein the wireless device is further
configured to bundle the first and second HARQ processes over four
transmit time intervals.
7. The apparatus of claim 6, wherein the first HARQ process and the
second HARQ process are allocated to different physical
resources.
8. The apparatus of claim 6, wherein the wireless device transmits
the first and second HARQ packets using semi-persistent
scheduling.
9. An apparatus for improving a coverage of an uplink Voice over IP
(VoIP) transmission of a wireless device, the method comprising:
means for assigning a first hybrid automatic repeat request (HARQ)
process to a first VoIP packet of the wireless device; means for
assigning a second HARQ process to a second VoIP packet of the
wireless device; and means for transmitting the first and second
VoIP packets from the wireless device to a base station.
10. The apparatus of claim 9, further comprising means for bundling
the first and second HARQ processes over four transmit time
intervals.
11. The apparatus of claim 10, wherein the first HARQ process and
the second HARQ process are allocated to different physical
resources.
12. The apparatus of claim 10, wherein the first and second HARQ
packets are transmitted using semi-persistent scheduling.
13. A system for improving a coverage of an uplink Voice over IP
(VoIP) transmission, the apparatus comprising: a wireless device
configured to: assign a first hybrid automatic repeat request
(HARQ) process to a first VoIP packet of the wireless device;
assign a second HARQ process to a second VoIP packet of the
wireless device; and transmit the first and second VoIP packets
from the wireless device to a base station.
14. The system of claim 13, wherein the wireless device is further
configured to bundle the first and second HARQ processes over four
transmit time intervals.
15. The system of claim 14, wherein the first HARQ process and the
second HARQ process are allocated to different physical
resources.
16. The system of claim 14, wherein the wireless device transmits
the first and second HARQ packets using semi-persistent
scheduling.
17. An apparatus for improving a coverage of an uplink Voice over
IP (VoIP) transmission of a wireless device, the method comprising:
means for assigning a first hybrid automatic repeat request (HARQ)
process to a first VoIP packet of the wireless device; means for
assigning a second HARQ process to a second VoIP packet of the
wireless device; and means for transmitting the first and second
VoIP packets from the wireless device to a base station.
18. The system of claim 17, further comprising means for bundling
the first and second HARQ processes over four transmit time
intervals.
19. The system of claim 18, wherein the first HARQ process and the
second HARQ process are allocated to different physical
resources.
20. The system of claim 18, wherein the first and second HARQ
packets are transmitted using semi-persistent scheduling.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a method and system to
enhance the coverage of uplink packet voice application--Voice over
IP (VoIP). Specifically, the invention relates to assigning
multiple hybrid automatic repeat request (HARQ) processes
simultaneously for one VoIP user.
[0002] With new technologies such as advanced multi-antennas,
carrier aggregation, orthogonal frequency division multiple access
(OFDMA), system capacities of cellular networks have been increased
significantly. The voice application was traditionally carried over
circuit switch networks, with dedicated physical channels. Once the
dedicated channel is allocated to a user, it remains to be reserved
for that user until the call is ended. To meet the ever growing
demand for data traffic, the wireless networks are migrating from
circuit voice switch to packet switch. The emerging 4G cellular
networks would be full IP serviced, including for voice. The voice
application carried over IP networks is called VoIP. Compared to
circuit switch voice, VoIP allows dynamic resource allocation to
match the voice activities and multiple voice users can compete for
the same resources during the calls. Speed coding study shows that
when a user is talking over the phone, there is no voice activity
for about half of time during which the user is either pausing or
remaining silent to listen. VoIP traffic is only allocated with
physical resources when the user is in talk spurt, thus
significantly improves the resource utilizations. Advanced
technologies such as HARQ can be applied for VoIP so that the
transmission can adapt to the fast fading of the channel, thereby
saving radio resources. With the above features, VoIP generally can
increase the voice capacity of a system compared to circuit switch
voice.
[0003] Although VoIP can deliver higher capacity of voice, its
coverage is generally poorer than circuit switch voice. The main
reason is the discontinuous transmission of VoIP packet.
Discontinuous transmission is a fundamental characteristic of data
transmission in 3G and 4G cellular networks. By restricting a data
packet within a short transmit time interval (TTI) for example in
the order of 1 millisecond, dynamic scheduling can be efficiently
carried out. The short TTI also enables fast HARQ retransmission,
with round trip time (RTT) in the order of 8-10 milliseconds, which
is helpful for link adaptation to fast fading. Since 3G and 4G
wireless standards are wideband, typical of 5.about.20 MHz, the
short TTI provides finer granularity for resource allocation at
least in time domain, so that smaller packet can also be
efficiently scheduled. It also fits the bursty nature of data
traffics. However, short TTI and bursty transmission are not
favourable to users at cell edges where the coverage is often
limited by the maximum transmit power of the terminals for uplink
traffics.
[0004] The coverage issue of uplink VoIP is studied in Release 8
LTE and the solution is through TTI bundling. Basically, instead of
using only one TTI (one millisecond), a VoIP packet is transmitted
over 4 TTIs. The adjective "bundling" stresses the fact that these
four TTIs are consecutive and the packet would stick to the same
physical resources over 4 TTIs. By spreading over 4 TTIs, much
lower modulation order and code rate can be used, compared to using
just one TTI. Therefore, the uplink VoIP coverage can be
improved.
[0005] Even with 4 TTI bundling, the coverage of VoIP still cannot
match that of circuit switch voice. For example, in 3G UMTS, the
TTI of circuit switch voice is 20 milliseconds. In LTE, the TTI of
VoIP with TTI bundling is 4 milliseconds. Given that voice packets
from upper layer would arrive at physical layer every 20
milliseconds during a talk spurt, the over-the-air transmission
should be finished within 20 milliseconds, to avoid the
accumulation and delay at the transmission queue. The round trip
time (RTT) in the case of 4 TTI bundling is a little longer than
without TTI bundling, in the order of 12 to 16 milliseconds. That
means the transmission should be finished with two HARQ
transmissions. So effectively, about 8 milliseconds are spent on a
VoIP packet transmission, which is significantly shorter than 20
millisecond TTI of UMTS circuit switch voice. In another word, the
issue of discontinuous transmission is not completely solved by TTI
bundling, which leads to the remaining gap in coverage between
circuit switch voice and VoIP.
SUMMARY OF THE INVENTION
[0006] In accordance with one aspect, the present invention
comprises a method of improve the uplink coverage of VoIP by
assigning multiple HARQ processes simultaneously for a VoIP user
during a talk spurt. Each VoIP packet is assigned an HARQ
process.
[0007] According to the present invention, different physical
resources can be allocated for different HARQ processes of a VoIP
user.
[0008] According to the present invention, semi-persistent
scheduling can be applied to either one of the HARQ processes for a
VoIP user.
[0009] According to the present invention, TTI bundling can be
applied to either one of the HARQ processes for a VoIP user.
[0010] In another aspect, the invention comprises a system whose
VoIP uplink coverage can be improved by assigning multiple HARQ
processes for a VoIP user. The system comprises different physical
resources allocated for different HARQ processes of a VoIP user,
with possible semi-persistent scheduling and TTI bundling in either
one of the HARQ processes.
BRIEF DESCRIPTION OF THE FIGURES
[0011] FIG. 1 shows an example of assigning multiple HARQ processes
simultaneously for a VoIP user.
DETAILED DESCRIPTION OF THE INVENTION
[0012] The invention considers improving the continuity of VoIP
transmission by assigning multiple HARQ processes simultaneously
for one VoIP user during a talk spurt. In conventional VoIP, one
HARQ process is assigned for each VoIP user, in order to simplify
the MAC layer and physical layer processing. Since the round trip
time (RTT) of HARQ is at least 8 ms, using only one HARQ process
results in transmission gap between HARQ (re)transmissions, even
when 4 TTI bundling is used.
[0013] The invention is illustrated in an example shown in FIG. 1.
Two HARQ processes are allocated for this particular VoIP user that
is in a talk spurt. Upon two VoIP packets arrive from the upper
layer, each VoIP packet would be assigned with an HARQ processes,
i.e., VoIP packet 1 is assigned HARQ proc_id=0, with lighter gray
color. VoIP packet 2 is assigned HARQ proc_id=1, with darker gray
color. Packet 2 is transmitted 4 milliseconds after Packet 1 is
transmitted. One TTI or one subframe (SF) equals one millisecond.
4-TTI bundling (over 4 consecutive subframes) is applied to each
HARQ process. Different HARQ processes can use different physical
resources as seen in FIG. 1. Semi-persistent scheduling is assumed
where the physical resources for each HARQ process remain the same
for both initial transmissions (1.sup.st HARQ) and retransmissions
(2.sup.nd HARQ). The round trip time is 8 milliseconds. By
assigning two HARQ processes simultaneously, there is only a gap of
4 milliseconds when there is no transmission at all, significantly
smaller than assigning only one HARQ process at a time.
[0014] FIG. 1 is just one example. In fact, it is found that if
8-TTI bundling is allowed, the gap can be completely eliminated by
assigning two HARQ processes simultaneously for a VoIP user.
[0015] It should be understood that the methods and devices of the
present invention may be executed employing machines and apparatus
including simple and complex computers. Moreover, the architecture
and methods described above can be stored, in part or in full, on
forms of machine-readable media. For example, the operations of the
present invention could be stored on machine-readable media, such
as magnetic disks or optical disks, which are accessible via a disk
drive (or computer-readable medium drive). Alternatively, the logic
to perform the operations as discussed above, could be implemented
in additional computer and/or machine readable media, such as
discrete hardware components as large-scale integrated circuits
(LSI's), application-specific integrated circuits (ASIC's),
firmware such as electrically erasable programmable read-only only
memory (EEPROM's); and the like. Implementations of certain
embodiments may further take the form of machine-implemented,
including web-implemented, computer software.
[0016] Many modifications and alterations of the new methods and
systems described herein may be employed by those skilled in the
art without departing from the spirit and scope of the invention
which is limited only by the claims.
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